Line Bore - What is the biggest you have used?

[Augie]

I know they offer huge oversize bearings for line bores, up to five cuts, but was wondering what the biggest size you have used. The most I have ever used is second cut, but have a case that needs a third cut and am hesitant to go that big. I think second cuts are already pushing the life of a case. This one needs a third plus a second thrust cut. Time to look for another case?

[keifernet]

Depends on what you expect out of the engine... if it is just stock .060/.080 thrust works fine... as long as the case is not warped or has other issues.

If it is higher performance then NO I would not recommend it... although I have built some larger displacement engines on cases that were bored that big at someone elses insistance... their case and parts, they did not want to buy a new case...

I have had some other engine builders I respect say they have used even .080 .080 stating that " all it means is you won't be building it again when this one's blown" and some say that their are shops who go up to .100... they used to make those big bearings...maybe still do but I have never used them...my cutters only go to .080

And then there are the folks that say that a case is disposable and should not even be considered if it is align bored. Standard/ or new cases only.

It's entirely up to you. If you can afford a new or a better used case and you are planning a higher than stock performance motor then go for it.

[gt1953]

No more then .080 if at all possible keep it .040.
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[RUI FARIA]

I have seen bearings (Metal Leve) that are 3mm (.120) oversize with a 2mm (.040) oversize flange, so I guess this size line bore can be done. I agree with the others this could work on a stock motor but I would not recommend it for anything else. One point of interest is that I had a Type 1 case machined to fit a larger rear main bearing (Type 4) to fit a crank from a WBX motor and that was 5mm (0.20) larger than the standard Type 1 bearing and it runs great, no problems.

[sushinav]

I'm newish to the Hipo engine scene. There seems to be a good division of opinions on the new vs line bored concept. Is cost savings that significant line boring a case?
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[keifernet]

[nsracing]

While a new case is very pretty, it ain't that accurate. Strength, however, is better on new cases.

If we are just talking about figures of how straight the mains and roundness of holes and bearing crush, the new cases will have a hard time competing against a beautifully alignbored case.

A used case is a used case. Of course it is seasoned and probably tired. That is called metal-fatigue. It just will not be as strong as a new one.

I have alignbored cases to over 0.080 for 411 mains. Now this is some alignbore work. The rough cuts are done on a Kwik-way boring bar and the final cut the TruLine Alignborer.

For small engines, the alignbored used cases will be fine. Provided you have the mains with good alignment, good round holes, good bearing crush and decent surface finish. It can't look like a large drill bit just went through it.

For bigger motors in a used case? There is always shuffle pins!!!! Pin the whole mains all the way across. This makes a very stiff case.

Good luck.

[VolkDubz]

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We go up to .080 on the thrust and .060 on the align bore. Never had a problem. Cases, bearings, engines are not smart. They don't have brains. They don't know what size the holes are cut to. Would I build a 2276 with 212/60 bearings? Probably not, but nothing wrong with doing that on 1914 and smaller.
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[vwracerdave]

.040/std is the biggest I will go on any stroker crank engine. I will not build a stroker engine on a case with a cut thrust, or any performance engine that requires a stronger pressure plate. Once you cut the thrust you fatigue the metal to the point where it will continue to deteriorate very quickly. The most I will go to rebuild a stock engine is a 60/40 case if it's just used beater parts. Anything past that gets junked.
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So much depends on who is doing the line bore. A good job will include using the crank and bearings THAT ARE TO BE USED IN THE ENGINE, and match the cut to the case, crank, bearings.

Many (most) shops run the tool through and call it "good", without actually checking. Blackline Racing (for example), will cut the case, then carefully measure everything. Then they'll swap bearings if needed (brands usually) until the proper clearance is achieved. Or cut it another .0005" to reduce crush, etc. Yes it's a pain, which is why most shops do not do this. But the good ones will insist.

I don't use line bored cases, but with the prices of new cases, a lot of guys have no choice.

Not doing these checks during the machining is part of the reason for line bored engines having the reputation they do (hot, low oil pressure, etc). A guy can build an engine with a new case, and if the bearing clearances are wrong it can seize or run hot and have low oil pressure too. You must check!
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[BIGMIKEY]

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agree to disagree. It absolutely affects the crush of the bearing, and the bearing clearance, if that matters to you.

Around 20% of the NEW OEM VW cases need to be line bored to Standard, to get the bearing clearance correct. Sometimes the cutter only skims part of the bore, but the gauges don't lie.

Also, the torque of the main studs on the case changes how much the cutter takes off. If you want to cut more, just torque them another 5lbs prior to the cut. Sometimes the bores are simply not round. It's just a matter of checking.

I'm sure Nick will pipe in here with details on how he does it.
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All you have said is that .0005" tighter/looser than spec is ok with you. If that's the way you do it, fine.

I don't know why you continue with the Ad Hominem attacks.

Simply post your opinion on the subject at hand, and leave it at that. If it differs from mine, that's ok.

While the OEM line bore issue is "not a newsbreak to you", the World doesn't revolve around you. I was posting it for the new guy that does NOT know this fact. There are a lot of guys not aware of it.
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So, when I post something it's an opinion, yet when you post it's a "fact"?

I'm not going to get sucked into your Troll work. Have a nice day.
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[mark tucker]

I would never try to bore a std case, thats just asking for problems. I seem to remember a hotvw&bugies ar tickel on this fancy motor they were building.and did just that because they wanted the bore perfectly straight....well they effed it up. if you think you can take one of these boring bars and perfectly center it so it only takes off the high spots....and make it round withen specs ...well I think your the high spot. you have the centering cones/jig the slop in the bar/bush on 2 ends,boogers,burrs, wear on the bar&bush,deflection,bend,warp,the guy holding the drill or how the case is jiged up or loaded more on one side or the other, whatever. but your gonna screw it up.not worth the effort or chance of screwing it up.Im pertty good but Im not stupid.Ive seen a lot of screwed up stuff that the screwer told them selvs now it's right,just to make them selvs feal good or not want to replace it... whatever it's still screwed up and should be re done to the next size. when I checked my new aluminum case it was good to go.as was my nos mag case even though the deck was not square as both cylinders were tilted inward toward each other on one side.thats an easy fix.
if you have a new case that isant right find out why has it been droped and the pins have shifted? it's not easy to bore a out of round hole with good machines.

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